Technogical dilemna

I can't start my blog this week without saying how sad the passing of Nelson Mandela was.  So much has been written and said about him this week. but I would just like to mention one of his famous quotations which I like. "Do not judge me by my successes, judge me by how many times I fell down and got back up again."  There's a message there for all of us.
As you now I have always preached you should "listen to your body" but I decided to take this to a higher level by buying some new technology - there's always room for more technology IF it helps your performance!  Friends often are concerned that I might be overdoing my training as the mileage starts to build up but this might help prevent problems.  For the athlete's out there here's a bit of science. 
I bought the ithelite HRV monitor and app.  It measures the heart rate variability (HRV) which assesses the effects of stress on your body. It is measured as the time gap between your heart beats that varies as you breathe in and out - you measure it 1st thing in the morning and last thing at night. Research evidence increasingly links high HRV to good health and a high level of fitness, whilst decreased HRV is linked to stress, fatigue and even burnout.  If you get a green reading then go for it in your training session, amber means reduce the intensity and red means take the day off.  Here's a link to the science. http://myithlete.com/the-science-behind-hrv.html
However it has given me a dilemna.  Having conducted measurements for over a week now I have had 3 red readings.  On each occassion I've felt ok then realised I have had a slight head cold.  Is the equipment that accurate or am I imagining things?  I ran on Saturday under an amber reading.  I was on my own, taking it easy but feeling, or thinking I was feeling, not 100%.  I had decided to only do 5 miles (one lap) when a fellow triathlete (Derek Boyd) joined me.  What a difference having some company made.  I realised I would have to do 2 laps because that was the original plan and I didn't want to let Derek down.  The pace also crept up and at the end, it had been a good but not too strenuous workout.
So this morning I was meant to head out for a hard 10 mile hill run.  The reading was, you guessed it, red and again the head cold was there but really not much.  So reluctantly I called the run off and rested but it has been annoying me.  The concept of reducing or not training when you are not 100% makes sense but when I am really only running at the weekends and it coincides with that then it's a bummer.
I am going to persevere with the technology for the month of December as it's not a heavy training month and I can evaluate the variables.  Come January the mileage will start to pick up on the swimming and the running as will the hours on the turbo trainer so I want to make sure I am in good nick (as oposed to "Old Nick"!).